Description

Learn how to make Tag bindings bidirectional so value changes write back to the Tag.

Video recorded using: Ignition 7.7

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[00:00] In order for an operator to be able to write back to a tag, like turn a machine off or changing a setpoint, we have to be able to bind a component bidirectionally to the tag. So say, for example, I come over here to my tag database and I go down and find this N7:9 tag. I can drag it onto my screen and I can select control and I can do maybe a two state toggle button to turn it on or off. So here in Ignition, if I go into preview mode, and I actually click the button, I turn it off, you can see the value gets written back to the tag. I turn it on. You can see it goes back to one. This is only made possible because the binding is actually bidirectional here. So if I go down to the control value property here of this component and go to the bind, you can see it's bound to a tag, N7:9, but down at the bottom the bidirectional checkbox is checked. So what happens here is when Ignition writes the values of the property, because it's bidirectional, we take that value and write it back to the tag. As you can see, when I do that, a dash line around the component is there, letting me know that the write is pending. As soon as it completes, that line goes away. Now if I was to go and take a component myself, like over here I take a slider component, and I want to link it to one of these tags. In order for it to actually write the value back, we have to make it bidirectional. So I go to my value property of the slider and bind it to a tag, I select, let's say, N7:13. If I don't make it bidirectional and I press okay, if I change the value of the slider, you can see that it won't do anything to N7:13. It's still a value of 50 even though it's down here at a lower value. I do have to go into the binding and make it bidirectional for that to get reflected. So now if I make it bidirectional, press okay, if I change the value of the slider, the dash line around the component let's me know the writes pending. You can see that that value got written to the tag. That dash line is very important. It let's you know that the binding was set up correctly. So what's really happening here in Ignition, is that for any property, let's say for a numeric text field, when your operator is changing a value, if I type a word like hello in here, it's actually writing that value to the property of that component. And if I don't do any bidirectional on the binding, it's just going to stay on the component. It won't go any further. But if I make it bidirectional, it takes the same value and then writes it to tag automatically for you. So you want to make sure, if you're doing any control components, to have that box checked.

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